2 digit years using strptime() is not able to parse birthdays very well.

Question

Consider the following birthdays (as dob):

• 1-Jun-68
• 1-Jun-69

When parsed with Python’s datetime.strptime(dob, '%d-%b-%y') will yield:

• datetime.datetime(2068, 6, 1, 0, 0)
• datetime.datetime(1969, 6, 1, 0, 0)

Well of course they’re supposed to be born in the same decade but now it’s not even in the same century!

According to the docs this is perfectly valid behaviour:

When 2-digit years are accepted, they are converted according to the POSIX or X/Open standard: values 69-99 are mapped to 1969-1999, and values 0–68 are mapped to 2000–2068.

I understand why the function is set up like this but is there a way to work around this? Perhaps with defining your own ranges for 2-digit years?

Answer 1

If you're always using it for birthdays, just subtract 100 if the year is after now:

if d > datetime.now():
    d = datetime(d.year - 100, d.month, d.day)

Answer 2

If you're expecting a birthday, you could always just manually massage the data - any date in the future is automatically set back a century, or some such.

Answer 3

This function shifts the year to 1950:

def millenium(year, shift=1950):
    return (year-shift)%100 + shift